Steam generator



FIG. 1 is a back, left, top perspective view of a steam generator;

FIG. 2 is a front, left, top perspective view thereof;

FIG. 3 is a back elevational view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a right elevational view thereof; and,

FIG. 8 is a left elevational view thereof.

The broken lines in the drawings form no part of the claimed design. 

CLAIM The ornamental design for a steam generator, as shown and described. 